1. Field of the Invention
This invention relates generally to semiconductor processing, and more particularly to scanning probe tips and methods of making the same.
2. Description of the Related Art
Atomic force microscopy generally involves scanning a stylus or probe across a microscopic topography, such as an integrated circuit structure, and sensing the forces exerted on the stylus. The stylus is provided with a small geometry tip that physically contacts the surface topography. The technique has been widely used in metrology of structures in photoresist, interlevel dielectric layers, sidewall angles, trench depths and surface morphology. The scanning resolution of the probe is dependent on the radius of curvature of the probe tip that contacts a given topographical feature.
Early conventionally fabricated probe tips were composed of sharpened silicon. Even after multiple oxidation and etching sharpening steps, such conventional tips had a tip radius of curvature of over 10.0 nm. Tips of such size work well in scanning features of greater than 10.0 nm in lateral dimension. However, the trend in micro machining and integrated circuit fabrication is toward further miniaturization.
Carbon nanotubes have been proposed as an alternative to conventionally fabricated probe tips. Single-walled carbon nanotubes have diameters on the order of 1.0 nm and may be formed with aspect ratios as high as 1000:1. There is thus the potential for better resolution. Carbon nanotubes have a high bulk modulus such that mechanical strength is not necessarily sacrificed even at such small geometries.
Despite these advantages, accurate growth of carbon nanotubes has proved to be a technical challenge. In a conventional process, chemical vapor deposition is used in conjunction with a catalyst that serves as a seed site for tube formation. However, the growth kinetics are not well understood. As a result, conventionally fabricated carbon nanotubes frequently form with irregular shapes and in seemingly random directions. The final tube structures often resemble the antlers of a deer.
The present invention is directed to overcoming or reducing the effects of one or more of the foregoing disadvantages.
In accordance with one aspect of the present invention, a method of fabricating a microscopy probe is provided that includes providing a member and forming a film on the member. The film fosters growth of carbon nanotubes when exposed to a carbon-containing compound. The member is exposed to an electric field. A carbon nanotube is formed on the film. The electric field causes the carbon nanotube to form in a preselected direction.
In accordance with another aspect of the present invention, a method of fabricating a microscopy probe is provided that includes providing a member and forming a first film on the member. The first film fosters growth of carbon nanotubes when exposed to a carbon-containing compound. A second film is formed on the first film. The second film has an opening therein that exposes a portion of the first film. A carbon nanotube is formed on the exposed portion of the first film.
In accordance with another aspect of the present invention, a method of fabricating a microscopy probe is provided that includes forming a member on a substrate and forming a first film on the member. The first film fosters growth of carbon nanotubes when exposed to a carbon-containing compound. A second film is formed on the first film. The second film has an opening therein that exposes a portion of the first film. A carbon nanotube is formed on the exposed portion of the first film. The member is separated from the substrate.
In accordance with another aspect of the present invention, a microscopy probe is provided that includes a member and a first film on the member. The first film fosters growth of carbon nanotubes when exposed to a carbon-containing compound. A second film is positioned on the first film. The second film has an opening therein that extends to a portion of the first film. A carbon nanotube is provided that has a first portion positioned in the opening and coupled to the exposed portion of the first film.